1. Field of the Invention
The present invention relates to a polarizing film and a method for manufacturing a polarizing film.
2. Description of the Related Art
Polarizing films are placed on both sides of a liquid crystal cell of a liquid crystal display apparatus as a typical image display apparatus, the placement being attributable to an image-forming mode of the apparatus. For example, the following method has been proposed as a method of manufacturing the polarizing film (for example, Japanese Patent Application Laid-open No. 2000-338329). A laminate having a resin substrate and a polyvinyl alcohol (PVA)-based resin layer is stretched, and is then subjected to dyeing treatment so that the polarizing film may be formed on the resin substrate. According to such method, a polarizing film having a small thickness is obtained. Accordingly, the method has been attracting attention because of its potential to contribute to thinning of an image display apparatus in recent years. However, enhancement of optical characteristics (such as polarization degree) of the thin polarizing film obtained by such method involves a problem of durability in that a crack is liable to be generated at the time of heating.